SRC/dlantr.f(3)

NAME
SRC/dlantr.f

SYNOPSIS

  Functions/Subroutines
double precision function dlantr (norm, uplo, diag, m, n, a, lda, work)
DLANTR returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular matrix.

Function/Subroutine Documentation

  double precision function dlantr (character norm, character uplo, character diag, integer m, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) work)

DLANTR returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular matrix.

Purpose:

    !>
    !> DLANTR  returns the value of the one norm,  or the Frobenius norm, or
    !> the  infinity norm,  or the  element of  largest absolute value  of a
    !> trapezoidal or triangular matrix A.
    !>

Returns
    DLANTR

    !>
    !>    DLANTR = ( max(abs(A(i,j))), NORM = 'M' or 'm'
    !>             (
    !>             ( norm1(A),         NORM = '1', 'O' or 'o'
    !>             (
    !>             ( normI(A),         NORM = 'I' or 'i'
    !>             (
    !>             ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
    !>
    !> where  norm1  denotes the  one norm of a matrix (maximum column sum),
    !> normI  denotes the  infinity norm  of a matrix  (maximum row sum) and
    !> normF  denotes the  Frobenius norm of a matrix (square root of sum of
    !> squares).  Note that  max(abs(A(i,j)))  is not a consistent matrix norm.
    !>

Parameters
    NORM

    !>          NORM is CHARACTER*1
    !>          Specifies the value to be returned in DLANTR as described
    !>          above.
    !>

    UPLO

    !>          UPLO is CHARACTER*1
    !>          Specifies whether the matrix A is upper or lower trapezoidal.
    !>          = 'U':  Upper trapezoidal
    !>          = 'L':  Lower trapezoidal
    !>          Note that A is triangular instead of trapezoidal if M = N.
    !>

    DIAG

    !>          DIAG is CHARACTER*1
    !>          Specifies whether or not the matrix A has unit diagonal.
    !>          = 'N':  Non-unit diagonal
    !>          = 'U':  Unit diagonal
    !>

    M

    !>          M is INTEGER
    !>          The number of rows of the matrix A.  M >= 0, and if
    !>          UPLO = 'U', M <= N.  When M = 0, DLANTR is set to zero.
    !>

    N

    !>          N is INTEGER
    !>          The number of columns of the matrix A.  N >= 0, and if
    !>          UPLO = 'L', N <= M.  When N = 0, DLANTR is set to zero.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension (LDA,N)
    !>          The trapezoidal matrix A (A is triangular if M = N).
    !>          If UPLO = 'U', the leading m by n upper trapezoidal part of
    !>          the array A contains the upper trapezoidal matrix, and the
    !>          strictly lower triangular part of A is not referenced.
    !>          If UPLO = 'L', the leading m by n lower trapezoidal part of
    !>          the array A contains the lower trapezoidal matrix, and the
    !>          strictly upper triangular part of A is not referenced.  Note
    !>          that when DIAG = 'U', the diagonal elements of A are not
    !>          referenced and are assumed to be one.
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(M,1).
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)),
    !>          where LWORK >= M when NORM = 'I'; otherwise, WORK is not
    !>          referenced.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 139 of file dlantr.f.

Author

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